I just bought a beautiful Sherpa backpack carrier... its awesome. For 2 3lb dogs it would be awesome and it sits on your back making it so much easier to carry them. For MY dogs its a bit tight, one of my boys is 8lbs and the other is 5lbs though so its a pretty big difference from your 2.
How do you know your new one is going to be 3lbs though? are you just wanting this carrier for the puppy days? or to be useful their whole lives? You don't know how big your dog will get though so in the end you may end up getting another carrier after all. good luck!!
here is mine
http://www.sherpapet.com/products/de...ddetail_post=Y